1. Field of the Invention
The present invention relates generally to an energy efficient closure system for minimizing loss of thermal energy through openings such as horizontally extending furnace entry openings and the like that are used to admit charges of material to treatment chambers, and is particularly well suited for use with entry openings of reheat furnaces through which slabs, billets or blooms of steel must pass so as to be admitted to furnace chambers wherein they are heated to proper temperatures to enable the steel members to be "worked" or otherwise formed into desired configurations. Heated slabs, for example, typically are processed through a rolling mill to form coils of steel stock.
One aspect of the preferred practice of the present invention relates to methods and means for minimizing convection and radiation heat loss through a furnace entry opening during passage of an elongate member therethrough as by utilizing a plurality of depending, inwardly curved, insulated door components that are arranged in a side-by-side array extending across the furnace opening, with each of the components being independently pivoted in response to being engaged by an underlying portion of an elongate member that is being fed through the furnace opening.
Another aspect of the preferred practice of the present invention relates to methods and means for enhancing the thermal efficiency of a side-by-side array of insulated, inwardly curved, pivotally mounted door components by utilizing a hanging curtain of flexible insulation that complements and cooperates with insulation that is carried by the door components. Still other aspects of the preferred practice of the invention reside in methods and means that are utilized to support the door components and the curtain, in the use of relatively narrow but relatively thickly insulated door components at selected locations along the door component array, and in features of the construction and mounting of the curved, insulated door components.
2. Prior Art
Large industrial apparatus for effecting thermal treatment of sizable charges of material that are admitted sequentially to and discharged sequentially from a thermal treatment chamber often are provided with inlet and outlet openings located on opposite sides of the treatment chamber. It is well known to provide such apparatus with insulated closures of various types for selectively opening and closing the inlet and outlet openings. Proposals of various types have been made to form insulated closures in component parts that are separately mounted for independent movement.
In conjunction with the art of steel making, it is well known to utilize what is referred to as a "reheat furnace" to sequentially heat steel slabs, billets or blooms to desired temperatures to enable these heated masses of steel to be "worked" or otherwise formed into predetermined configurations of steel stock. A reheat furnace typically has a treatment chamber that is capable of receiving a plurality of preformed slabs, billets or blooms of steel..sup.1 The slabs to be heated typically are fed through the treatment chamber relatively slowly in a direction of travel that extends from an inlet or entry opening located on one side of the treatment chamber to an outlet or exit opening located on an opposite side of the treatment chamber. Typically, each "slab" comprises an elongate quantity of steel that measures about twenty to twenty five feet in length, and has a generally rectangular cross section measuring about eight to eleven inches in thickness and about forty to about seventy inches in width. FNT .sup.1 For simplicity, the term "slabs" will be referred to during the remainder of this discussion. However, as those who are skilled in the art readily will understand, the present invention is not limited to use with steel slabs. Rather, the processing of "steel slabs" is discussed herein simply as being indicative of one example of a charge of material that can be fed through entry door structures that embody features of the present invention.
While steel slabs tend to be relatively flat and straight, it is not unusual to encounter a slab that is twisted or bowed, or that has a non-uniform cross section. Thus, while inlet or entry openings to reheat furnaces usually do not need to be terribly tall to admit slabs therethrough, there are occasions when a twisted, bowed and/or non-uniform slab needs portions of the entryway opening to be taller than normally would be required by the median thickness of the material that forms the slab. This need presents a challenge to those who seek to conserve thermal energy by providing furnace entry doors that open only to the extent that is needed to accommodate an entering slab.
Although proposals have been made to form door structures of thermal treatment apparatus in sections that are arranged to open only to the extend needed to permit the passage therethrough of a charge of material to or from a treatment chamber, there remains a need for a door that is formed from a plurality of independently movable door components wherein each of the components opens only to the extend that is needed to permit passage of an engaging segment of material that is moving through the opening that is controlled by the door. Because steel slabs entering a reheat furnace tend to vary in length, thickness and in a variety of other ways; and, because slabs tend not to be perfectly centered with the opening of a reheat furnace when passing therethrough, there remains a need for a plural-segment entry door that will work well with a reheat furnace to open only if and to such extent as may be needed as slabs are fed in sequence through the entry opening of the furnace.
A further problem that is associated with providing components for use within the vicinity of the entry openings of reheat furnaces is that the intensity of the heat energy that tends to dissipate through such openings is of such a magnitude that special materials need to be utilized that resist thermal degradation; and, depending on the exposure that such materials receive, they may need to be provided with water cooling in order to assure service lives of reasonable length. Furthermore, inasmuch as structures that are positioned within the vicinity of the entryway opening of a reheat furnace sometimes are subjected to impacts by mis-aligned or mis-fed slabs, such structures need to have a capability to withstand such impacts if they are to provide suitable service lives.
The related Annealing Cases that are referenced above disclose the use of furnace components formed from nodular cast iron, and place emphasis on the use of nodular cast iron as a material that is particularly suitable for withstanding impacts within the high temperature environments of steel treating furnaces. Moreover, these cases disclose the use of water cooling in steel treatment furnace environments to enhance the longevity of furnace components. However, these cases do not address such needs as are addressed by the present invention including, for example, the longstanding need for improved methods and means to admit material to a treatment chamber through an entry opening while conserving the thermal energy of a treatment chamber environment.
The Exit Door Patents that are referenced above disclose the compressive packing and clamping of insulation material that is supported at least in part by nodular cast iron components, and wherein clamping of refractory insulation is, in some instances, effected by utilizing expanded metal structures. However, these cases also do not address such needs as are addressed herein, including, for example, the longstanding need for a novel and improved multi-segmented entry door that is well suited for use with steel reheat furnaces and the like.